Here we give a brief summary of the classic SAV schemes.
The main idea of SAV is to reformulate the energy functional (REF ) in the quadratic form
by introducing an appropriate SAV.
The framework of the classic SAV schemes is based on a linear splitting of the energy functional
and, as shown in [1]}, a suitable stabilization term is usually also introduced in such splitting
so that the numerical simulations can provide satisfactory results for highly stiff problems in practice.
